Apparatus for refining metals by electricity



(Nb Model.) A

C. R. FLETCHER. APPARATUS FOR REFINING METALS BY ELECTRICITY.

No. 484,416. Patented Oct. 18, 1892.

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Wzbwsaas: fwi A/fw To all whom it may concern:

UNITED STATES CHARLES R. FLETCHER, OF

APPARATUS FOR REFINING BOSTON, MASSACHUSETTS.

M ETALS BY ELECTRICITY.

SPECIFICATION forming part of Letters Patent No. 484,416, dated October 18, 1892. Application filed November 25, 1891. Serial No. 413.044. (No model.)

Be it known that I, CHARLES R. FLETCHER, a citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Apparatus for Refining Metals by Electricity, of which the following is a specification, reference being had to the drawings accompanying and forming a part of the same.

The apparatus which embodies my present improvements comprises a tank or vat for containing the electrolyte or electrolytic sol ution, one or more cathodes for receiving a deposit of metal, and one or more anodes which are dissolved by the action of an electric current and transferred to and deposited upon the cathode or cathodes.

The object of the present invention is to obtain pure from impure metal, separating the impurities therefrom, and is especially applicable to copper, which in the crude form, as anodes, contains insolubleimpurities,which it is very desirable to separate from the metal, and, if of value, to recover. My purpose, therefore, is mainly to avoid the defects which exist in the apparatus heretofore used and which lessen the value of such apparatus in electro-refining processes by permitting these impurities to be carried over and attached to the cathodes.

The accompanying drawings, which illus trate my improvements, will now be referred to, and the novel features of my invention will be pointed out.

Figure 1 is a vertical central longitudinal section of an apparatus embodying my invention. Fig. 2 is a cross-section of the same on a plane parallel to and between the plates. Fig. 3 is a top plan view of one of the plates. Fig. 4 is a perspective of a plate of impure metal.

I employ a number of thick plates A A of impure metal, supported in series in a tank or vat B, which contains a suitable electrolyte. To these plates, which are, properly speaking, the anode-plates, I attach cathodeplates 0 of thin metal, which in copper refining are of pure copper and smooth on their surface. I prepare these plates in a special manner; but so far as the present invention is concerned they may be prepared in any suitable manner, and it need only be said that they are considerably wider and longer than the corresponding anode-plates and have all their edges that reach into the electrolyte rounded or curved, so as to surround and inclose the edges of the anode-plates. The plates 0 are attached to the plates A by any suitable means-as, for example, clamps D. The anode and attached cathode plates are inclined slightly from the perpendicular, but with the impure-metal or anode surface uppermostthat is to say, they are arranged so that the upper edge of the cathode-surface shall be inclined toward the perpendicular or in the direction of the anode-plate facing it, which latter also has its surface inclined from the perpendicular. In this manner the lower or exposed surfaces of the plate 0 become the cathode-surfaces, while the upper or exposed surfaces of the anode-plates become the anode-surfaces, the under surfaces of the anode-plate resting upon the cathode sheets or plates.

Any convenient means-such as blocks or bars E and rests Fmay be employed for supporting the plates in the vat. In fact, any of the common devices used for supporting such bodies either fixedly or adj ustably in the electrolyte may be employed for this purpose. The electrical connections from a suitable source of electricity G are made to the end plates of the series, respectively, and of course it will be understood in this arrangement that the cathode sheet or plate may be omitted from the first of the series or that connected with the positive pole of the source of current, while at the other end the anode plate of impure metal may be dispensed with. The current is brought to the first anode-plate and passes thence through the electrolyte lengthwise of the tank horizontally from one anode to the opposite cathode-sheet, thence on to the final cathode, which is connected to the source of current. The number of anodes and cathodes will depend upon the conditions of the particular plant.

The several advantages of the invention result from the particular construction and arrangement above described, and consist in the increased rapidity of work on account of the augmented cathode-surfaces, the fact that a purer product is obtained because the oathode sheets or surfaces are inclined toward and hence above the anode-surfaces instead of away from and hence below the same, and the freedom from electrolytic growths or warts, as they are sometimes called, which are apt to collect on sharp edges.

I have discovered that by curving or bending the edges of the cathode-surfaces, as described, these peculiar and undesirable growths do not appear. Under ordinary circumstances they render the product not only unsightly, but often grow with such rapidity in the solution as to reach out to the opposite anode-surface, which disturbs if not destroys the proper action of the apparatus and sometimes even causes the destruction of the armature of the dynamo-machine furnishing the current; I find that this advantage is gained whenever the cathodesurface is rounded or curved in the manner described, and this feature of the invention is applicable to cases where no independent cathodesurfaces aroused, but plates of impure metal employed the opposite surfaces of whichconstitute the anode and cathode surfaces, repectively. In such cases such plates maybe cast with curved backs and edges, and in the use of the same the metal is deposited upon the backs and dissolved ofi from the upper inclined surfaces of the same.

I am aware that apparatus of this general character has been proposed in which the plates have been placed in inclined positions and connected with the source of current in such manner as to constitute the under surfaces anodes and the upper surfaces cathodes, and dissolving the pure metal from the anodesurfaces and depositing it upon the cathode- I surfaces. The reason for such an arrangement is not apparent, and my experience has led me to believe that it is inadvisable- I have found that the upper surfaces of the plates when thus made cathodes or cathode surfaces become rough, squareedged, and coated with a somewhat insoluble oxide of high resistance, which covers the copper or other metals when cast in the open air, and

the inclined upper surfaces constituting the cathodes are liable to collect and retaiufioating and settlingim purities, which are the very particles I wish to separate from the metals. Obviously by my arrangement I am enabled to place the plates nearer together without fear of the impurities rising from the, anode up to the cathode surfaces, and thus Idiminish the total resistance of the tank and render more economical the process of electrorefining.

In conjunction with the plates above described I employ jets of the electrolyte from flattened nozzles H, which are arranged to quietly wash the impurities down the inclined anode-surfaces to the bottom of the tank. By thus cleansing the anodes with the electrolyte they are not so liable to becomehoneycombed .as when this precaution is not adopted. By my method when the anode becomes thin and a time arrives when it would naturally disintegrate and fall in pieces into the electrolyte and upon the cathode if inclined in the opposite direction with the anode surface undermost'itis sustained and supported by the thickened cathode-sheet, which has I am able to use with better advantage the cleansing jets of electrolyte. This plan is superior to that generally adopted of cleansing the cathode-surfaces with jets of air orsteam, as the air rises in bubbles, which touch only here and there temporarily, while steam heats the electrolyte at the anode-surfaces, thus producing disturbing conditions. my improvements, also, cast anodes, which are found to be more soluble than rolled metal, as they are more porous and open, and hence more easily attacked by the liquid electrolyte, several inches in thickness, and to remove the cathode-plates, substituting new cathode-sheets at frequent intervals and without dist-urbing the anode or disturbing the operation going on in any vat. When the back surface of intermediate plates constitute cathode-surfaces, the deposited metal. sometimes attaches itself so firmly that it can be removed only with great difficulty and only by removing the plate from the vat. This difficulty frequently presents itself even in thecase of anode-plates cast with rounded backs, as above described, and shown in Fig. 4; but by the use of the attached cathode-plates I am enabled to remove the cathode-slabs easily and of varying thickness, according to pleasure or the requirements of the market. the smoothness of the enlarged cathode-sur- I am enabled to use face and the curved edges of the same in the electrolyte I attribute, mainly, the excellent results in refining metal which I have secured with the above apparatus. When the cathode-plates are sulficiently built up, they are removed from the vat and'run through suitable rolls to straighten them out andfiatten. the curved edges, whereby they are reduced to a shape more convenient for transportation.

What I claim is- 1. In an electrolytic apparatus for refining metals, the combination, with the vat or tank, of independent plates arranged in series,each, except the first and last of the series, being composed of an anode-plate of theimpure metal to be refinedand an attached cathode plate or sheet of similar metal in a pure state longer and wider than the impure plates, as set forth.

2. The combination, in an apparatus, with a vat or tank for containing an electrolyte, of a series of independent elecposition, the uptrode-plates in an inclined electro-refining.

per or anode portions or sides of the same being composed of plates of the impure metal to be refined and the under or cathode portions being composed of thin sheets of the same metal in a pure state and of greater length and width than the impure portions, the two portions of said plates being secured together, as set fort 3. In an electro-refining apparatus in which the electrodes or plates are so arranged as to constitute anodes on one side and cathodes on the other, the combination, in each plate, except the first and last of the series, of an impure anode-plate and a thin cathode-plate J backing the same andhaving curved or rounded edges that inciose the anode-plate, as set forth.

4. The combination, with the series of inclined compound plates, each consisting of an upper anode surface or plate of impure metal and an under cathode surface or plate of purer thin metal, of nozzles or jets for delivering from above streams of the electrolyte upon the upper or anode surfaces of the plates for cleansing the same, as set forth.

5. The combination, in an electro-refining tank, of two or more electrode-plates, the opposite sides of which constitute anode and cathode surfaces, respectively, the cathode sides or surfaces being formed with edges curved or rounded toward the anode side, as and for the purpose set forth. 7

CHARLES R. FLETCHER.

Witnesses:

WM. H. ELDRIDGE, H. G. YOUNG. 

